1. Field of the Invention
The present invention relates to a continuously variable transmission, and more particularly to a transmission which can convert and transmit the power of an engine to comply with the load on the output shaft without engaging, or disengaging the gears with a shift lever.
In general, a transmission device converts and transmits the power generated by an engine to comply with the load placed on the output shaft. Prior art transmission devices utilize a hand-operated shift lever and a foot-operated clutch to cut the power between the input side receiving the power from the engine and the transmission device in order to accomplish a shifting of the gears. Automatic transmissions are those which do not need a foot clutch.
A continuously automatic transmission device which makes it possible to convert and to transmit power without a clutch by using a combination of differential gears consisting of ring gears, planetary gears and sun gears, is described in U.S. patent application Ser. No. 347,916, filed May 5, 1989. Further, another continuous transmission uses a combination of bevel gears and worm gears and is fully described in a U.S. Pat. No. 3,770,879 by Thomas A.W.K. Watson.
However, such transmission devices fail to provide smooth transmission steps and utilize a complicated structure. Hence there is a need for the development of a transmission device which provides excellent capability and simple structure.
The object of the present invention is to provide a continuously variable transmission which is very efficient, capable of converting and transmitting power to the output shaft in a smooth and stepless manner while being mechanically simple in design.